Updated

A remote-controlled "cleaning" robot that entered one of three wrecked Fukushima reactor containment chambers was withdrawn before completing its mission due to glitches most likely caused by high radiation.

Tuesday's mission was the first time a robot entered the chamber since the March 2011 tsunami critically damaged the nuclear plant.

Tokyo Electric Power Co. said the intent was to inspect and clean a passage before another robot does a fuller examination later this month.

The robot went only partway into a space under the core that TEPCO wants to inspect closely. The outcome means the second robot will encounter more obstacles and have less time for examination.

Images recently captured from inside the chamber showed damage and structures coated with molten material, possibly mixed with melted nuclear fuel.